On Saturday, two days out from the final Group B match at AAMI Park, Kerr pulled the boots on for the first time since injuring her left calf on July 19, then confirmed she was able to return.
A win would seal progression to the round of 16 while a draw means the Matildas would rely on Ireland beating Nigeria, likely by at least two goals.
Australia would be knocked out if they lost to Canada.
"Obviously I'm really happy that she did put the boots on today and that she's available for Monday," Carpenter told reporters.
"It's a massive boost for us to get obviously our captain, our leader and just a world-class player back in our squad.
"Mentally it's massive. Having more players available and having Sam obviously available, it brings so much to our team and obviously also a lot to the opposition knowing that we have Sam available for this game.
"So I think she's doing everything in her right to be herself on Monday and we all as a team are really excited to have her back in the squad and yeah, back on the pitch."
Kerr wouldn't be drawn on how many minutes she could play.
Fellow striker Mary Fowler is poised to return from concussion.
"Obviously having Sam available, having Mary available, they're two of our world-class strikers back in the selection pool, back in the squad so having them coming into our squad is a massive boost," Carpenter said.
"At the end of the day it's just being clinical in front of goal. And we know that's what we need to be, on our A-game on Monday night.
"We need players to step up, we need players to rise to the occasion. It's a pressure moment and I know for a fact that we obviously have our backs against the wall and it's a do-or-die.
"For us, I think we're better in those situations when we're the underdogs and we have everything to fight for. So everyone needs to give their heart and no matter what happens we have to stick together."
Kerr watched the 1-0 win over Ireland and 3-2 defeat to Nigeria from the bench.
"Sam's obviously a great leader, a great captain and having her on the other side it's obviously unique for her. It's a different situation she's never been in before," Carpenter said.
"But for us as a team, we really felt her there on the sideline.
"She's always been behind us obviously during training and off the field, on the field."
